In humans, the lack or deficiency in iodine leads to particularly important pathological disorders whose principal ones are, on the one hand, goiter and its complications (deglutition disorders, respiratory disorders, cancer formation, collateral circulation) and, on the other hand, hypothyroidism and its complications (cretinism, cerebral disorders, premature deliveries, miscarriages, congenital anomalies).
Even if iodine deficiency has disappeared in the industrialized countries, this is not the case in developing countries (Latin American countries along the cordillera of the Andes, and the non-coastal countries of Africa and Asia).
Of the different methods proposed for remedying this deficiency, the most effective one consists in adding iodine to the water for domestic use (drinking, washing, irrigation) which most frequently is made available by wells and drillings.
Many studies have shown that a daily supply of about 100 .mu.g of iodine equivalent per day and per person would be sufficient for preventing the development of endemic goiter.
Because it is known that an individual takes up on average 2 liters of water per day, it is desirable that one liter of treated water should contain at least 50 .mu.g per liter of iodine.
There are various systems which make the controlled release of iodine into well or drilling water possible, and it is of particular importance to be able to control the effective iodine content in water.